This invention relates generally to systems for diagnosing oral diseases in mammals, and more particularly, to a colorimetric diagnostic test for periodontal disease activity in a human being, or an animal.
Periodontal disease is the major affliction of the human dentition. Today, more teeth are lost to the effects of periodontal disease than to caries (tooth decay). Periodontal disease is a group of conditions affecting the gingiva (gum) and the bones that support the teeth. The primary cause of periodontal disease is bacterial plaque which causes an inflammation of the gum which may result in actual destruction of tissue. In some cases, destruction of the bone occurs to the point where teeth lose their attachment thereto.
In periodontal disease, there is usually a large accumulation of bacteria in plaque attached to the tooth, both above (supragingival) and below (subgingival) the gum line. This plaque can become calcified in its depths, forming what is known as calculus. This plaque and associated calculus can create a pocket between the teeth and the gingiva which is characteristic of the disease. Presently, periodontal disease is diagnosed by clinical observation of indicators such as the presence and depth of pockets, loss of attachment of the teeth to the bone, and papillary bleeding of the gums. Clinical observations, however, are not always reliable indicators. For example, deep pockets are not necessarily infected by bacteria capable of causing inflammatory tissue destruction (periodontopathic bacteria). Unfortunately, there are currently no reliable, inexpensive, and objective means for determining whether or not the pocket is infected with periodontopathic bacteria.
The lack of a diagnostic test has been a serious problem, particularly in view of the severity of the corrective measures typically required to be taken to treat periodontal disease. Such measures can include, the excising of diseased gum tissue so as to expose and debride affected roots and to eliminate pockets. Recently, more conservative surgical treatment has been developed which typically involves detaching a flap of gum from the tooth, cleaning the freshly exposed tooth surface of all calculus and plaque, and then suturing the gingiva back together over the cleaned surface. Both surgical approaches work equally well as long as the patient continues to have professional maintenance treatment.
Although periodontal disease has traditionally been defined as an inflammation of the gums, which means that host tissue is responding to bacteria and/or the products of bacteria, periodontal disease has not been treated like a bacterial infection in the medical sense. For example, periodontal disease has not been treated in the art with antimicrobial drugs because the growth of plaque on the teeth appears to be inevitable and since it is external to the body, would not seem to be treatable by systemically administered drugs. Moreover, it was not believed that periodontal disease was specific to one, or several, particularly damaging bacteria. In fact, about 200 species of microbes have been isolated from various plaque samples. Thus, mechanical treatment which requires instrumenting of the tooth to remove accumulated bacterial deposits non-specifically was deemed to be the appropriate means of treating periodontal disease.
It has been reported that periodontal disease is characterized by a progressive loss of tooth supporting tissue which occurs when the periodontal pocket is colonized by a preponderance of gram negative anaerobic bacteria (see, e.g., Loesche, et al., "Role of Spirochetes in Periodontal Disease," Host-Parasite Interaction in Periodontal Disease, Genco and Mergengagen, eds., American Society of Microbiology, Washington, D.C., 1982, pages 62-75 and Slots, "Importance of Black Pigmented Bacteroides in Human Periodontal Disease," Ibid., pages 27-45). Spirochetes and black pigmented bacteroides (BPB) are particularly prominent when pockets bleed upon probing and when there is clinical evidence of disease progression. Thus, the possibility of drug treatment directed towards these anaerobic organisms is raised. In fact, beneficial results have been observed with the use of metronidazole, an antimicrobial effective against anaerobes. Metronidazole is available under the trademark FLAGYL from G. D. Searle & Co., Chicago, Ill. 60680 as well as in generic form from Zenith Laboratories, Inc., Ramsey, N.J. The use of drugs, in the treatment of periodontal disease has accentuated the need for an objective means of detecting the presence of anaerobic periodontal infection since some of the clinical symptoms, such as pockets, will still be observable in drug-treated patients, but may not necessarily be infected. Thus, there exists a need in the art for a simple, reliable test for monitoring the efficacy of drug therapy.
Bacteriological diagnosis of elevated levels of spirochetes and BPB by cultural methods can only be done in the research laboratory at the present time. Certain types of the spirochetes, however, cannot be grown in a culture with existing technology.
The spirochetes can be diagnosed by microscopic examination using either phase contrast or dark field condensers. One prior art technique used for the diagnosis of periodontal disease involves the microscopic examination of the plaque for determination of the presence of motile forms, mostly spirochetes, and thereby assesses the need for escalating or terminating therapy [see, Keyes, et al., "Diagnosis of Creviculoradicular Infections," Ibid., pages 394-403 and Listgarten, et al., J. Clin. Periodontal., Vol. 8, pages 122-138 (1981]. However, no similar microscopic procedure exists for the identification of BPB. Thus, the dentist/clinician must presently resort to the purchase of expensive microscopes and associated video equipment and/or have available sophisticated research laboratory facilities in order to make necessary assays and measurements for the presence or absence of bacteriological parameters that correlate to periodontal disease.
In view of the present state of the art, there is a great need for a reliable and inexpensive test system for identifying the presence of periodontal disease activity due to anaerobic bacteria. There is additionally a need for a test system which can conveniently be performed by a dentist/clinician. Such a test system would be of significant value in advising a patient of his or her condition, as well as monitoring the effectiveness of treatment.
In a previous patent application, U.S. patent application Ser. No. 740,097 filed May 31, 1985 and assigned to the assignee hereof, a simple and inexpensive diagnostic test for periodontal disease is described wherein the proteolytic activity of a specimen of suspected periodontopathogenic bacteria is measured. More specifically, this assay method operates to detect the presence of trypsin-like activity, illustratively in a specimen of subgingival plaque. In one embodiment of that invention, a chromogenic test substance comprises an amino acid or a peptide substrate combined with a chromosphore which is hydrolyzable by trypsin-like enzymes in the specimen to release a chromophore. Detection of a color change due to said release indicates whether such trypsin-like activity is present, and hence, whether or not periodontal disease is present.
One problem with the aforementioned technique is that a minimum number of microorganisms should be present in the specimen in order for the results of the test to be a reliable indication of the presence of periodontopathic organisms. It is a feature of the invention described in U.S. patent application Ser. No. 740,097 that the sample size, or content, does not have to be quantified or measured. This aspect of that invention contributes significantly to its simplicity. However, color development is a function of the total number of bacteria which possess the trypsin-like enzyme that are present in the sample. Thus, if the specimen itself is small, and consequently contains less than the minimum number of such microorganisms, then the test procedure may produce a false negative result even though periodontal disease-producing microorganisms are present in the specimen.
Accordingly, it is an object of this invention to provide an improved diagnostic test for determining the presence of periodontal disease.
It is another object of the invention to provide a diagnostic test system which can identify periodontal disease and which does not require clinical observation so that the disease can be detected at an incipient stage at which it is not yet clinically observable.
It is a further object of the invention to provide a diagnostic test for detecting the presence of, inter alia, Treponema denticola, Bacteroides gingivalis, Bacteroides forsythus, Capnocytophaga gingivalis and other organisms in the plaque which possess trypsin-like enzyme activity.
It is also an object of the invention to provide a diagnostic test for periodontal disease which can be performed in the office of a dentist/clinician by unskilled personnel, and which does not require expensive or special equipment.
It is an additional object of the invention to provide a diagnostic test for periodontal disease which is reliable.
It is a further additional object to provide a diagnostic test for periodontal disease which yields an indication of the reliability of the diagnostic test results for a particular patient.
It is yet another object of the invention to provide a diagnostic test for periodontal disease which can be used to monitor the virulence of infection.
It is yet a further object of the invention to provide a diagnostic test for periodontal disease which can be performed easily as part of a patient's regular periodic check-up, for epidemiological surveys, for screening examinations, such as military screening, and for monitoring treatment efficacy on periodontal patients.
It is still another object of the invention to provide a diagnostic test for periodontal disease which is capable of detecting anaerobic bacteria under aerobic conditions.
It is still another object of the invention to provide a diagnostic test for periodontal disease which does not require culturing of bacterial specimens, and which will test directly a sample of plaque or other such specimen.
It is additionally an object of the invention to provide a convenient assay kit which can be used in the diagnosis of periodontal disease.
It is additionally a further object of the invention to provide a colorimetric diagnosis system where by the presence of periodontal disease is determined by a color change.